NL2021008B1 - Trailer length adjustment - Google Patents

Abstract

Semi-trailer with extendable chassis provided with two tubular profiles that are telescopically slidable with respect to each other and provided with a locking mechanism for blocking the two tubular profiles relative to each other. The blocking mechanism comprises a blocking pin which is adjustably connected to the first box section. The second sleeve profile is provided with a series of holes. Each hole of the series of holes in the second sleeve profile has a unique hole shape orientation and / or has a unique transverse position with respect to a longitudinal direction of the second sleeve profile. The position and / or rotational orientation of the blocking pin relative to the first box section is adjustable such that the blocking pin for each hole of the series of holes can be brought into a unique position and / or rotational orientation associated with that hole and so that an end of the blocking pin can only reach into the associated associated hole for blocking the telescopic sliding of both tube profiles.

Description

Θ 2021008 © B1 PATENT (2?) Application number: 2021008 (22) Application submitted: 29 May 2018 (51) Int. Cl .:

B62D 21/14 (2018.01) B62D 21/20 (2019.01) (30) Priority:

(J) Application registered:

December 2019 (73) Patent holder (s):

Broshuis B.V. in Kampen (72) Inventor (s):

Baltasar Johannes Petrus Broshuis (43) Request published:

in Kampen

Patent granted:

December 2019 (45) Patent issued:

December 2019 (74) Agent:

ir. H.A. Witmans et al. In The Hague (54) Semi-trailer length adjustment (57) Semi-trailer with extendable chassis provided with two tubular profiles that are telescopically slidable with respect to each other and provided with a blocking mechanism for blocking the two tubular profiles relative to each other. The blocking mechanism comprises a blocking pin which is adjustably connected to the first box section. The second sleeve profile is provided with a series of holes. Each hole of the series of holes in the second sleeve profile has a unique hole shape orientation and / or has a unique transverse position with respect to a longitudinal direction of the second sleeve profile. The position and / or rotational orientation of the blocking pin relative to the first box section is adjustable such that the blocking pin for each hole of the series of holes can be brought into a unique position and / or rotational orientation associated with that hole and so that an end of the blocking pin can only reach into the associated associated hole for blocking the telescopic sliding of both tube profiles.

NLB1 2021008

This patent has been granted regardless of the attached result of the research into the state of the art and written opinion. The patent corresponds to the documents originally submitted.

P119019NL00

Title: Length adjustment trailer

FIELD

The invention relates to a trailer with a length-adjustable chassis, as well as a method for adjusting a trailer with an extendable chassis in length.

BACKGROUND

A trailer with a chassis that is adjustable in length is already known from GB 1,189,809. GB 1,189,809 shows an extendable chassis. The extensibility is provided by at least one extension assembly provided with a first and a second box section that are telescopically slidable relative to each other in a longitudinal direction. The extension assembly is provided with a locking mechanism for blocking the first and the second box section relative to each other. The blocking mechanism comprises a blocking pin which is adjustably connected in an axial direction of the blocking pin transversely of the longitudinal direction to the first tubular profile and is thereby movable between a locking position and a release position. The second sleeve profile is provided with a series of holes which are arranged at different length positions with respect to the second sleeve profile. If a user of the trailer wants to change the length of the trailer, he must unlock the blocking mechanism by removing the pin against spring action from a hole in the second box section. He can then pull the trailer with a towing vehicle and thereby cause the two tube profiles to shift relative to each other. The pin then shoots into the next hole of the second tube profile under the influence of the spring action. If the user does not want the pin to be locked in the next adjacent hole but in a subsequent hole, he must come out of the cab to unlock the locking mechanism again and then pull the trailer again with the towing vehicle. GB

1,189,809 shows a trailer with two extension assemblies. After the first extension assembly has been set to the correct length in one or more steps, the user should perform the same method for the second extension assembly. Therefore, before the user has adjusted the trailer to the correct length, he must in most cases climb out of the cab a number of times in order to unlock the locking mechanism.

RESUME

The object of the invention is to provide a trailer with an extendable chassis, which can be adjusted in length simply and quickly.

To this end, the invention provides a trailer according to claim 1. More in particular, the invention provides a trailer comprising an extendable chassis. The extensibility is provided by at least one extension assembly provided with a first and a second box section that are telescopically slidable relative to each other in a longitudinal direction. The extension assembly is provided with a locking mechanism for blocking the first and the second box section relative to each other. The blocking mechanism comprises a blocking pin which is adjustably connected in an axial direction of the blocking pin transversely of the longitudinal direction to the first tubular profile and is thereby movable between a locking position and a release position. The second sleeve profile is provided with a series of holes at different length positions with respect to a longitudinal axis of the second sleeve profile. Each hole of the series of holes in the second sleeve profile has a unique hole shape orientation and / or has a unique transverse position with respect to the longitudinal axis of the second sleeve profile. A position and / or rotational orientation of the blocking pin relative to the first box section is adjustable in a direction transverse to the axial direction of the blocking pin, such that the blocking pin for each hole of the series of holes is in a unique position associated with that hole and / or rotative orientation is achievable. In that particular unique position and / or rotational orientation, the blocking pin can be moved axially to the locking position so that one end of the blocking pin can reach into the relevant hole for blocking the telescopic sliding of the first box profile relative to the second box profile. The end of the blocking pin cannot be brought into the other holes in the series of holes in that particular unique position and / or rotational orientation.

In order to adjust the trailer in length, the locking pin must be brought out of a hole in the second tube profile and, after the tube profiles have been displaced relative to each other, be brought into another hole. Before it has reached the desired hole, the blocking pin can pass through one or more holes during the displacement of the sleeve profiles without being able to move into it. By combining a unique hole shape orientation and / or a unique transverse position of the holes with a unique position and / or rotational orientation of the blocking pin, it is possible to pre-select in which hole the blocking pin must move. By adjusting the blocking pin in a unique position and / or rotational orientation, it is no longer possible for it to move in a different, undesired, hole. The locking pin will only be able to move in a hole once it has arrived at the hole associated with its unique position and / or rotational orientation. The blocking pin will therefore not be able to move in another hole and thereby fix the trailer in an undesired length. The locking pin therefore does not have to be removed from a hole again before the sleeve profiles can be moved further. Removing the locking pin from a hole several times is not necessary. It is sufficient to bring the locking pin once into the release position and to adjust it to the desired unique position and / or rotational orientation associated with the hole corresponding to the desired length of the chassis.

The invention further provides a method for adjusting the length of a trailer with an extendable chassis according to claim 15. More in particular, the invention provides a method comprising providing a trailer according to the invention, providing a towing vehicle coupled to the semi-trailer, adjusting the locking pin of the at least one extension assembly to a desired unique position and / or rotational orientation, and moving the towing vehicle until the locking pin of each of the at least one extension assembly is in the locking position.

The advantage of the method is that a user of the trailer only has to set the trailer once. He can place the blocking pin in the unique position and / or rotational orientation that corresponds to the length of the trailer he wishes. If the semi-trailer comprises several extension assemblies, the user can adjust the locking pins thereof in one go. By subsequently driving the towing vehicle to and fro, the user shifts the tube profiles relative to each other until the locking pin or locking pins are in the locking position. To this end, the user can, for example, secure a part of the trailer and move another part back and forth with the towing vehicle. For fixing the one part, for example, brakes of a possible chassis can be used. After the locking pin or locking pins are in the locking position, the trailer is ready for use and the user can drive away with the trailer.

Further elaborations of the invention are described in the subclaims and will be further elucidated hereinbelow on the basis of examples, with reference to the figures.

SHORT FIGURE DESCRIPTION

Figure la shows a top view of an example of the trailer according to the invention with the pin in a hole at a longitudinal position;

Figure 1b shows a side view of the example of Figure 1a;

Figure 2a shows a top view of the example of Figure 1a with the pin in a hole at a different length position;

Figure 2b shows a side view of the example of Figure 2a;

Figure 3 shows a top view of an example of the extension assembly according to the invention;

Figure 4 shows a cross section of the example of the extension assembly of Figure 3 along the line IV-IV in Figure 3;

Figure 5 shows a side view of an example of the second tube profile of the invention with the series of holes thereon;

Figure 6a shows a side view of an example of the blocking pin according to the invention;

Figure 6b shows a bottom view of the example of the locking pin of Figure 6a;

Figure 6c shows a front view of the example of the locking pin of Figure 6a.

DETAILED DESCRIPTION

In the following detailed description, reference numerals refer to the example shown in the figures. However, the embodiments described in the detailed description are not limited to the example shown in the figures, but may also be embodied in a different manner than shown in the example. The embodiments described in the detailed description should therefore also be read and understood without the reference numerals. The various embodiments to be described below can be used in combination with each other or independently of each other.

In a most general sense, the invention provides a trailer 10 comprising an extendable chassis 12. The extendability is provided by at least one extendable assembly 14 provided with a first 16 and a second 18 tubular profile which are telescopically slidable with respect to each other in a longitudinal direction. The extension assembly 14 is provided with a blocking mechanism 20 for blocking the first 16 and the second box section 18 relative to each other. The blocking mechanism 20 comprises a blocking pin 22 which is adjustably connected in an axial direction of the blocking pin 22 transversely of the longitudinal direction. with the first tube profile 16 and is movable therewith between a locking position and a release position. The second sleeve profile 18 is provided with a series of holes 24 at different longitudinal positions relative to a longitudinal axis 26 of the second sleeve profile 18. Each hole 24 of the series of holes 24 in the second sleeve profile 18 has a unique hole shape orientation and / or has a unique transverse position with respect to the longitudinal axis 26 of the second box profile 18. A position and / or rotational orientation of the blocking pin 22 relative to the first box profile 16 is adjustable in a direction transverse to the axial direction of the blocking pin 22, such that the blocking pin 22 for each hole 24 of the series of holes 24 can be brought into a unique position and / or rotational orientation associated with that hole 24. The blocking pin 22 is movable in that particular unique position and / or rotational orientation in the axial direction to the locking position so that an end 28 of the blocking pin 22 can reach into the relevant hole 24 for blocking the telescopic slidability of the first box profile 16 relative to of the second box section 18. The end 28 of the blocking pin 22 cannot be brought into the other holes 24 of the series of holes 24 in that particular unique position and / or rotational orientation.

The trailer 10 is adjustable in length, because it is provided with two tubular profiles 16, 18 telescopically slidable with respect to each other. It goes without saying that the tubular profiles 16, 18 are not limited to profiles with a rectangular cross-section, as shown in the example of the figures. The cross-section can, for example, also be round or hexagonal. Because the second box section 18 is provided with a series of holes 24 into which the blocking pin 22 can extend, the length of the trailer 10 can be fixed in different lengths. In order to adjust the trailer 10 in length, the blocking pin 22 must be brought out of a hole 24 in the second sleeve profile 18 and, after the sleeve profiles 16, 18 have been shifted relative to each other, into another hole 24. Bringing the blocking pin 22 out of a hole 24 will usually be done by a driver of a towing vehicle of the trailer 10. He / she will generally have to leave the cab of the towing vehicle for this. Subsequently, by moving the towing vehicle, he / she can make the box profiles 16, 18 move relative to each other until the blocking pin 22 reaches the desired hole 24. The blocking pin 22, while displacing the box profiles 16, 18, can pass through a plurality of holes 24, the shape and / or orientation of which does not correspond to the unique position and / or orientation of the blocking pin. By combining a unique hole shape orientation and / or a unique transverse position of the holes 24 with a unique position and / or rotational orientation of the blocking pin 22, it is possible to select in which hole 24 of the series of holes 24 the blocking pin 22 must extend. To adjust the trailer to the desired length, the user therefore only has to get out of the cab once to bring the locking pin to the release position and to a unique position and / or rotational orientation associated with the desired hole. It should be noted that the invention also comprises an embodiment (not shown) in which the locking pin is brought into the desired position and brought into the desired unique position and / or rotational orientation from the cabin, for example with a pneumatically or electrically actuated adjusting mechanism.

A first possibility to ensure that the blocking pin 22 can only reach into one hole 24 is to obtain a unique association between a position of the blocking pin 22 and a transverse / height position of a hole 24 in the second box section 18 with respect to the longitudinal axis 26. A unique position of the blocking pin 22 relative to the first box section 16 in a direction transverse to the axial direction of the blocking pin 22 can be obtained by making the blocking pin 22 movable in that direction. A second possibility to ensure that the blocking pin 22 can only extend into one hole 24 is to obtain a unique association between a rotational orientation of the blocking pin 22 and a unique hole-shape orientation of a hole 24 of the series of holes 24. A Unique hole shape orientation of each hole in the array of holes 24 can be obtained by giving the holes 24 a non-circle symmetrical hole shape and for each hole 24 arranging this non-circle symmetrical hole shape in the second tubular profile 18 in a different rotational orientation. An example of a non-circle-symmetrical hole shape is a non-equilateral triangle or a trapezium. The unique association is thereby achieved by giving the end of the blocking pin a shape that is exactly fitting for the hole shape of each hole 24 of the series of holes 24 and because the rotational orientation of the blocking pin 22 only fits the rotational orientation of one hole 24 from the series of holes. It is of course possible to use a combination of both possibilities, for example an embodiment in which the blocking pin 22 is both rotatable and can be displaced transversely / vertically with respect to the longitudinal axis.

By placing the blocking pin 22 in a unique position and / or rotational orientation, the user selects in which hole 24 the blocking pin 22 is to move, and thereby the user selects the desired length of the trailer 10. The extend assembly 14 can be provided with indications which indicates the associated length of the trailer 10 at a unique position and / or rotary orientation. The user can easily select the desired length on the basis of those indications. The blocking pin 22 will only reach into a hole 24 when it arrives at the hole 24 associated with its unique position and / or rotational orientation. By adjusting the blocking pin 22, it is no longer possible for it to extend into another, undesired hole 24. The blocking pin 22 will therefore not fix the trailer 10 to an undesired length.

In one embodiment, the position and / or rotational orientation of the blocking pin 22 is determined by the rotational orientation of the blocking pin 22 around an axis of rotation 30 extending in the axial direction of the blocking pin 22, and wherein the end 28 of the blocking pin 22 is eccentric is relative to the axis of rotation 30.

Because the end 28 of the blocking pin 22 is eccentric with respect to the axis of rotation 30, upon rotation of the blocking pin 22 the position of the end 28 will change in a direction transverse to the axial direction of the blocking pin 22. An example of such a locking pin 22 is shown in Figures 6a-6c. The end 28 has a rectangular shape therein. Because this end 28 is arranged eccentrically with respect to the axis of rotation 30, the position of the end 28 varies with rotation of the blocking pin 22. With a rotation of the blocking pin 22 of 180 °, the associated hole shape orientation, i.e. the rotational position of the hole, right. However, because the end is eccentric with respect to the axis of rotation 30, the transverse position of the associated hole 24 is not equal. Therefore, there is always a unique association between a position and / or rotational orientation of the blocking pin 22 and the hole shape orientation and / or transverse position of a hole 24.

In one embodiment, the blocking mechanism 20 is provided with a housing 32 which is fixedly connected to the first box section 16. The blocking pin 22 is received in the housing 32 and is movable within it in the axial direction and is rotatable around the axis of rotation 30.

By accommodating the blocking pin 22 in a housing 32, the movement of the blocking pin 22 can be limited to the desired, described movements.

In one embodiment, the blocking mechanism 20 is provided with a biasing unit 34 which, in operation, forces the blocking pin 22 in the axial direction to the second box section 18. The biasing unit 34 may, for example, be a spring which forces the blocking pin 22 to the second box section 22.

The biasing unit 34 ensures that the blocking pin 22 is continuously forced towards the second box section 18. It also ensures that when the blocking pin 22 comes to a hole 24 associated with the unique position and / or rotational orientation of the blocking pin 22, the blocking pin 22 is introduced into the hole 24.

In one embodiment, the blocking mechanism 20 may comprise a blocking actuator 36 which, in operation, displaces the blocking pin 22 in the axial direction. The blocking actuator 36 may, for example, be a pneumatic piston / cylinder assembly.

This embodiment can optionally be combined with the embodiment provided with the biasing unit 34. The blocking excitation then need only be configured to move the locking pin 22 against the action of the biasing unit 34 away from the second box section 18 in order to move it from the locking position to move to the release position.

In one embodiment, the trailer 10 is further provided with a chassis 38. The chassis 38 can consist of one or more axles provided with wheels extending transversely to the direction of travel. The number of axles and wheels will depend on the maximum weight to be carried by the trailer 10.

In one embodiment, the trailer 10 is further provided with a king pin 40 for attaching the trailer 10 to a towing vehicle. The kingpin 40 can be placed in a coupling dish of the towing vehicle to couple the trailer 10 to the towing vehicle.

In one embodiment, the trailer 10 is also provided with a locking mechanism 42. The locking mechanism 42 is provided with a locking pin 44 which is connected to the first sleeve profile 16, and a number of locking holes 48 in the second sleeve profile 18. Furthermore, the locking mechanism 42 is provided with a locking actuator 46 with the aid of which the locking pin 44 is movable between a release position in which the locking pin 44 does not extend in one of the locking holes 48 to a locking position in which the locking pin 44 extends into one of said locking holes 48. The locking mechanism 20 and the locking mechanism 42 are operatively connected by a tracking circuit which, in operation, energizes the lock actuator 46 and thereby moves the locking pin 44 into the locking position after the locking pin 22 has been brought into the locking position. The lock actuator 46 may include a pneumatic piston / cylinder assembly.

The locking pin 44 provides additional safety for the trailer 10. When the locking pin 22 extends into a hole 24 in the second box section 18, it ensures that the two box sections 16, 18 cannot shift relative to each other. In order to be able to guarantee safety, the box profiles 16, 18 must remain fixed on the public road while the trailer 10 is being driven. Depending on the loading of the trailer 10, forces on the locking pin 22, in particular when the trailer 10 is pulled up or braked, can become large. In order to further increase safety, the sleeve profiles 16, 18 can in addition to the locking pin 22 also be fixed by the locking pin 44. The follower circuit ensures that the locking pin 44 does not block the sleeve profiles 16, 18 until after the locking pin 22 in is locked.

In one embodiment, the at least one extension assembly 14 comprises two extension assemblies 14 which are provided one behind the other in the longitudinal direction. By placing two extension assemblies 14 one behind the other, the trailer can be moved apart in three parts.

In one embodiment, the extendable chassis 12 is extendable in three parts. The extendability is provided by the two extend assemblies 14. The blocking mechanism 20 of a first of the two extend assemblies 14 and the blocking mechanism 20 of a second of the two extend assemblies 14 are operatively connected by a follower circuit which, in operation, the blocking actuator 36 of the first actuates the extendable assembly 14 and thereby hold the locking pin 22 of the first extendable assembly 14 in the release position as long as the locking pin 22 of the second extendable assembly 14 has not moved into the locking position.

The effect is that when the towing vehicle travels to and fro when adjusting the length of the trailer, first the second extend assembly locks and then the first extend assembly locks. In the example shown in the figures, this effect can be achieved, for example, by having a tubular profile arranged on a rear part of the extendable chassis 12 continue into a tubular profile arranged on a front part of the extendable chassis 12. Both of the aforementioned profiles can be box profiles 16, 18 of one of the extension assemblies 14. The two aforementioned profiles can be provided with an air bellow / spring system that has a fixation position, in which the two profiles are fixed relative to each other, and a release position, wherein the two profiles are slidable relative to each other. The fixation of the profiles relative to each other can be achieved, for example, by means of friction. If the front part of the extendable chassis 12 is shifted when the air bellows / spring system is in the fixation position, then the rear part of the extendable chassis 12 slides along. If the rear section is blocked at the correct length, the air bellow / spring system can be set to the release position and the front section can be blocked at the correct length.

In one embodiment, the trailer 10 is configured for transporting containers, more in particular containers of different lengths. For this, the trailer can be equipped with one or more twistlocks to secure these containers.

The invention further provides a method for adjusting the length of a trailer with an extendable chassis according to the invention. More particularly, the invention provides a method comprising providing a trailer 10 according to the invention, providing a towing vehicle coupled to the trailer 10, adjusting the locking pin 22 of the at least one extendable assembly 14 in a desired unique position and / or rotational orientation, and moving the towing vehicle until the blocking pin 22 of each of the at least one extension assembly 14 is in the locking position.

The effects and advantages of the length adjustment method of a trailer are described in the summary and these effects and advantages are incorporated herein by reference.

The invention is not limited to the example shown in the figures. The embodiments described above can, as already indicated, also be designed differently than shown in the example of the figures. The scope of protection is defined by the following claims in which the reference numerals have no limiting effect.

LEGEND

- trailer

- chassis

- extension assembly

- first tube profile

- second box profile

- blocking mechanism

- locking pin

- hole

- longitudinal center line

- end (of the locking pin)

- axis of rotation

- housing

- biasing unit

- blocking assistance

- chassis

- kingpin

- locking mechanism

- locking pin

- locking assistance

- locking holes

Claims (15)

CONCLUSIONS A trailer (10), comprising an extendable chassis (12), wherein the extendability is provided by at least one extendable assembly (14) provided with a first (16) and a second (18) tube profile which is telescopic with respect to a longitudinal direction are displaceable from one another, wherein the extension assembly (14) is provided with a blocking mechanism (20) for blocking the first (16) and the second box section (18) relative to each other, the blocking mechanism (20) a blocking pin (22 ) which is adjustable in an axial direction of the blocking pin (22) transversely of the longitudinal direction and is movably connected to the first tube profile (16) and is movable therewith between a locking position and a release position, wherein the second tube profile (18) is provided with a series of holes (24) at different longitudinal positions with respect to a longitudinal axis (26) of the second box section (18), each hole (24) of the series of holes (24) in the second box section 1 (18) has a unique hole-shape orientation and / or has a unique transverse position with respect to the longitudinal axis (26) of the second box section (18), and wherein a position and / or rotational orientation of the blocking pin (22) with respect to the first sleeve profile (16) is adjustable in a direction transverse to the axial direction of the blocking pin (22), such that the blocking pin (22) for each hole (24) of the series of holes (24) in one with that hole (24) ) is associated with a unique position and / or rotational orientation in which the blocking pin (22) can be moved axially to the locking position so that an end (28) of the blocking pin (22) can reach into the relevant hole (24) for blocking the telescopic slidability of the first sleeve profile (16) relative to the second sleeve profile (18) and wherein the end (28) of the locking pin (22) in that particular unique position and / or rotational orientation is not in the remaining holes (24) of the series of holes (24) is deliverable. The semitrailer according to claim 1, wherein the position and / or rotational orientation of the blocking pin (22) is determined by the rotational orientation of the blocking pin (22) around a rotation center (30) which is in the axial direction of the blocking pin (22) 22), and wherein the end (28) of the blocking pin (22) is eccentric with respect to the axis of rotation (30). The trailer according to claim 2, wherein the blocking mechanism (20) is provided with a housing (32) fixedly connected to the first box section (16), the blocking pin (22) being received in the housing (32) and within it is movable in the axial direction and rotatable about the axis of rotation (30). The trailer according to any of the preceding claims, wherein the blocking mechanism (20) is provided with a biasing unit (34) which, in operation, urges the blocking pin (22) in axial direction towards the second box section (18). The trailer of claim 4, wherein the biasing unit (34) comprises a spring that urges the blocking pin (22) toward the second box section (18). The trailer according to any of claims 1-5, wherein the blocking mechanism (20) further comprises a blocking actuator (36) which, in operation, displaces the blocking pin (22) in the axial direction. The trailer according to claim 6, wherein the blocking excitation (36) comprises a pneumatic piston / cylinder assembly. The trailer according to any of the preceding claims, further provided with an undercarriage (38). The trailer according to any of the preceding claims, further provided with a kingpin (40) for attaching the trailer (10) to a towing vehicle. The trailer according to any one of the preceding claims, also provided with a locking mechanism (42), the locking mechanism (42) comprising: a locking pin (44) connected to the first sleeve profile (16); a plurality of securing holes (48) in the second box section (18) and a securing actuator (46) by means of which the securing pin (44) is movable between a release position in which the securing pin (44) does not extend in one of the securing holes (48) to a locking position in which the locking pin (44) extends into one of said locking holes (48), wherein the blocking mechanism (20) and the locking mechanism (42) are operatively connected by a tracking circuit which, in operation, actuates the locking excitation (46) and thereby The locking pin (44) moves into the locking position after the locking pin (22) has been brought into the locking position. The trailer as claimed in claim 10, wherein the locking actuator (46) comprises a pneumatic piston / cylinder assembly. The trailer according to any of the preceding claims, wherein the at least one extension assembly (14) comprises two extension assemblies (14) which are provided one behind the other in the longitudinal direction. The trailer according to claims 6 and 12, wherein the extendable chassis (12) is extendable in three parts, the extendability being provided by the two extend assemblies (14), the locking mechanism (20) of a first of the two extend assemblies ( 14) and the blocking mechanism (20) of a second of the two extension assemblies (14) are operatively connected by a tracking circuit which, in operation, energizes the blocking excitation (36) of the first extension assembly (14) and thereby the blocking pin (22) of hold the first extension assembly (14) in the release position as long as the locking pin (22) of the second extension assembly (14) has not moved into the locking position. The trailer according to any of the preceding claims, wherein the trailer is configured to transport containers, more in particular containers of different lengths. 15. Method for adjusting the length of a trailer with a 5 extendible chassis, the method comprising providing a trailer (10) according to any one of the preceding claims; providing a towing vehicle coupled to the trailer (10); - adjusting the locking pin (22) of the at least one extension assembly (14) in the desired unique position and / or rotational orientation; and moving the towing vehicle to the blocking pin (22) of each of the at least one extendable assembly (14) in the 15 lock position. 1/6 FIG. 1a FIG. 1b 2/6 FIG. 2b 3/6; ◄ IV «<-Ιν I I 4/6 46: ³⁶ ; ◄ v